Process for treating petroleum oils



W. M CROSS PROCESS FOR TREATING PETROLEUM OILS Filed Aug. 28, 1925 Dec.- 16, 1930.

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. NY dmnzma z3 d Patented Dec. 16, 1930 Tas Ulsu'rlezu STA PATENT OFFICE WALTER M. CROSS, OF KANSAS CITY, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO GASOLINE PRODUCTS COMPANY, INC.

- TION 0F DELAWARE 0F WILMINGTON, DELAWARE, A CORPORA- PROCESS FOB TBEATING PETROLEUM OILS Application led August 28, 1925. Serial No. 53,122.

This invention relates to improvements in` a process and apparatus fortreating petroleum oils and product produced thereby, and refers more particularly to a process in which oil is first raised to a conversion'temperature in a heating zone and thence passed to a conversion zone wherein the oil is maintained in a substantial body, the pressure beingbuilt upby evolved gases and maintained sufficiently high to prevent any substantial vaporization'of the oil during the heating and conversion thereof.

' This application-is in part' a continuation of a prior application Serial No. 594,493, filed October 14th, 1922.

Among further objects of the invention are, to provide a process in which Jthe oil, after being permitted to digest in the conversion chamber wherein the molecular rearrangement takes place whereby lighter hydrocarbons are contained in the oil in a state in which they may be readily separated therefrom by simple distillation, is passed to a separate distilling stage and relieved -of these lighter hydrocarbons under either atmospheric or superatmospheric ypress'ure; to provide a process in which certainl cuts of the distilled product may be rerun through the system to produce further conversion, and a process which, consists of a primary and secondary stage, the cracking taking place in the primary-stage wherein a synthetic product is formed' and a secondary stage in which thesynthetic product is relieved of its lighter ends. l

The process `further provides' a means whereby a combustion supporting gas is introduced along the bottom of the oil body ,in

the z one of conversion wherebya combination will be effected by the oxidized com- 4bustible'gases and the heavy polymers sep.

arated from the oil during the converslon thereof; to providea process by means of.

which an improved distillate is obtained being relatively high uin the percent of saturated compounds such as vthose of the aromatic series,'hydroxyl compound, benzol and aromatics.

source through the line 1 controlled by a valve 2, passed through the line 3 to a' pump 4 by means of which it is charged through the line 5 controlled by a valve 6 to the upper coil 7 situatedin the top compartment 8 of the furnace 9. The oil is circulated downwardly through this coil to the bottom tube of the upper coil 7 from which it passes into a transfer line 10 which is connected to the lower tube of the coil 11 mounted in the lower compartment of the furnace-9. In this lower compartment the oil receives the greater part of its heating and passes from the upper tube of the coil 11 through a transfer line 13 controlled by a valve 14 to the insulated conversion chamber 15 which is equipped with a pressure gauge 16 and a pyrometer 17. The oil is permitted to cool in a body in the chamber 15 and is maintained both in the heatin coils and the conversion chamber at su cient pressure to prevent any substantial vaporization. The pressure maintained is due to the evolution of vapors and gases. f At the opposite end of the conversion chamber, which is preferably constructed from a single ingot of forged steel and capable of withstanding high pressure at the higher temperatures necessary to produce the desired conversion, is a drawoff line 18 controlled by a val-ve 19 which connects the conversion chamber with ana/adjoining still 20. The latter still is mounted ab ve a furnace 21- preferably heated by means of a gas burner 22 which normally need not be fired Jas the heat contained in the oil will be suiicient to distill off the desired fractions at the reduced pressures maintained in the latter still 20. Theamount of oil drawn off through the line 18 serves to regulate the speed of flow of the oil through the conversion chamber.' This ow is controlled to permit the oil to have ample time to digest orv assume an equilibrium in the reacting chamber. This digestion consists.. primarily in a rearrangement of the molecules of the oil into a synthetic product which contains a larger percent of low boiling point hydrocarbons. To promote this reaction and to maintain the temperature in the conversion stage at the proper degree necessary to produce the product desired on or near the bottom of the chamber 15, is positioned a perforated pipe 21a which is controlled by a valve 22a. Through the perforations in this pipe may be introduced a combustion supporting gas or gases such as air or oxygen, in regulated quantities which create in their lpassage through the chamber a partial combustion of the separated polymerized products raising the temperature of the oil body toa point as high as that reached in the heatingstage or higher according to the desires of the operator. It is only essential that the oil in the heating tubes be heated to a temperature above its flash point to furnish conditions which are advantageous in the reaction chamber to the introduction of the combustion supporting gases. y duction of a combustion supporting gas to the reaction chamber, the temperature of conversion may be actually controlled. The possibility of reducing the temperature in the heating tubes greatly reduces the formation and collection of carbon in the hotter portions of the heating tubes, permitting the apparatus p to be run over a considerably longer period of time than heretofore by the practice due to the necessity of cleaning carbon from the heating tubes.

In addition to this, the introduction of a combustion supporting gas to the conversion.,

chamber serves to keep the oil in a turbulent and agitated condition, thereby keeping any carbon particles separated out through the digestion period in a suspended state and in a condition advantageous to combination with the gases after they are introduced to this conversion zone.- Maintaining the separated carbonaceous products in a suspended condition will reduce materially the accumulated or free carbon in the conversion chamber. Thus the synthetic product or the converted material drawn from the chamber l5 will' contain this solid material not consumed by combination with the air in a suspended state, and, after distillation in the still 20, the residual substances, consisting of the unvaporized oil and the carbonaceous matter, may be drawn oil' from the still through the line 23 controlled by a valve 24.

It is understood that these conversion chambers may be connected Withone or more stills so that the oil relieved from the reactlng chamber may be immediately subjected to distillation by a reduction of pressure to extract therefrom the lighter hydrocarbons.

A further advantage of this type of apparatus is the fact that there is less heat lost 1n the system as the synthetic product is im- Furthermore, by the intromediately introduced to a distillation stage into which it is passed and vaporization of a lighter product effected with the reduction of pressure which takes place on its passing through the reduction valve 19.

In Fig. 2 are shown alternate chambers 25 and 26 whichmay be used in place of the single reacting stage 15. 4In case the alternate chamber of the type shown is used the transfer line 13 will be connected to a header 27 having secondary connections 28 and 29 to the respec tive chambers. In a like manner, the draw off line 18 will be connected into a header 30 which is equipped with connections 31 and 32 tapped into the respective chambers 26 and 25. It is essential also that the valves be interposed in the respective connections 28 and 29, 31 and 32 in orderto control the How of liquids to cut out one chamber and cut in the other while one is being cleaned. It is understood, also, that separate perforated pipes will necessarily be positioned on the bottom of each of the alternate chambers if such an installation is desired.

With the reduction of pressure on the oil as it is introduced into the still 20, there will be immediately a considerable evolution of vapors and gases due to this pressure reduction and the contained heat in the oil. When operating normally on a common type of charging stock, it will be unnecessary to supply additional heat to the furnace 21. With certain oils, however, it will be necessary t0 add heat to the oil in the still 20. These oils will constitute higher boiling point fractions such as reflux products which are relatively difficult to vaporize. The operation of the still 20 will be governed primarily by the character of the oil used and also the quality of the distillate desired. In any event, there will be a substantial reduction of pressure from the reacting stage to the distillino' stage and conditions of pressure in the stil will range from atmospheric to considerably above atmospheric pressure.

The vapors evolved in the still pass off through the line`33 which is controlled by a throttle valve 34 and are introduced to the lower header of a refluxing condensing element 35.' These reiiux towers may take the form of harps as shown, dephlegmators, packed towers or bubble tower constructions in which are removed the higher boiling point fractions from the hydrocarbon vapors. The element 35 and the adjoining container 36 are identically the same in form consisting 'of the upper `and lower header which connects the tubes through which the vapors pass and are subjected to the cooling e'ect of the atmosphere. The vapors rise through the tubes inthe reflux container 35 and separate out the refiux condensate which passes down through the condenser coil 37 situated in the condenser box 38. The bottom end of the coil terminates in the line-39 regulated by a valve 40 which is in the condenser box 38. This coil is likewise connected by a line regulated by a valve 46 to the tank 41. VThese -vapors which remain uncondensed after passing through the element '36. are directed off through the line 47 in which is interposed a valve 48, and after passing through the condenser coil 49 are drawn ofil through the line .50 in which is in- Ill' terposed a valve 51 to a benzine storage tank not shown. The liquids collected by 'reflux condensation in the refluxcondensers 35 and 36 are combined and collected, as explained, in the tank 41 from which they may be drawn oil through the line 52 controlled by a valve 56 or may be directed back through the line 3 regulated by a.V valve 54 and charged with incoming charging stock to a pump 4 and for recirculation through the system.

The oil is circulated through the heating coil in the manner described and raised to a temperature ranging from 600 -to 900 F. It is then passed to the digestion orreaction stage where a temperature from 700 to 1,000

F. is maintained. The introduction of a comf bustion supporting gas facilitates the controlling of temperature in this latter stage. The oil from the conversion stage is passed to the still 20 wherein there is a reduction-of pressure'which is controlled by the valve 19. ln the still under normal operations 90% of the oil` passes over-head in the form'of vapors, while 10% condensates are removed through the reflux condensing stages and separate cuts made. The final product, is collected in a storage tank while the reflux condensate may becollected and 'rerun or'drawn off as desired.

It is recognized that it is old practice to introduce an indeterminate amor/int of air to a hydrocarbonbody at low pressure and distribute the air indiscriminately therein to keep up the temperature. It is also rec-l ognized that air has been introduced heretofore into oil bodies maintained at a cracking temperature and'pressures as high as 200 pounds per square inch to produce combustion of certain of the fractions in the body and prevent any considerable loss of heat subsequent to the transfer of the heated oil from the heating to the cracking stages.A The disadvantage of such practice is that air introduced indiscriminately in proper amounts as above mentioned consumes by combustion desirable products rich in hydrogen instead of polymerized products insoluble in the oil and 'ing to the character separated out during the conversion thereof inthe form of carbonaceous ,material Furthermore, air injected in this manner will increase materially'the formation ofsuch objectionable polymers.v If, however, the combustion supporting gas is introduced at a plurality of points along the bottom of the tconversion chamber, the desirable effect is emphasized by increasing the distribution and dispersion of the gas, thereby keeping down the degree of local concentration ofthe oxygen and oxidation will take place of more of those products insoluble in the oil, rich in carbon and lean in hydrogen.- Y

The novelty or discovery in the present invention lies in the fact that the tendency to form unsaturates under relatively high presl sures and temperatures with the introduction of a gas of this sort is minimized, While the v formation and production of saturated hydrocarbons and those of the aromatic series, hydroxyl compounds, benzol and other antidetonating compounds relatively indeterminate as to their molecular" structures, is` accentuated.

As explained, this system'is particularly adapted to the conversion or cracking of charging stock such as gas oil, kerosene distillates, oils which can be commercially treated under pressure to remove low boiling 'point products. \Preferably, the oil is treated to a temperaturei'n excess of 700 F. in the heating stage and held at, or above, this temperature fuel oil or other types ofin the cracking stage. Pressures of froml 600 to 2,000 pounds may be used. Pressures ranging from 600 to 1,000 pounds have given satisfactory commercial results.

f/ The production of anti-detonating compounds inthe, oil vdoes not mean that such products are merely present, but that they are present in a considerable quantity and in amounts that the recovered motor fuel is positively anti-detonating to a marked degree when tested fonthisproperty. There has been'produced, for instance, twenty to fifty percent benzol content in the cracked distillate resulting from the.conversion of A California oil at temperatures ranging from 700 to 900 F. and 700 to 900 pounds per square inch pressure Where heat was added to prevent heat loss in the conversion stage.

The product obtained by this process possesses marked anti-detonating propertieswhen used 1n an lnternal combustion engine due to the fact that itrcontains a large percentage of aromatics, hydroxyl compounds and benzol; the constituents varying accordof the oil treated and temperature and pressure conditions under which the particular oil is processed. At all events, there is, in the composition of the resultant product, a relatively high percentage of aromatic compounds with relation to thel olefin compounds. There is also a certain percentage of'combined oxygen produced in,

the oil body by the air or combustion supporting gas. This oxygen besides adding to the anti-detonating effect of the fuel when used atl'ords oxygen to the' consumed com'- bustible mixture reducing, and to a great extent eliminating, the creation and pres' ence of toxic gases such as carbon monoxidtl in'the exhaust gases. A minimum of air,

such as three-fourths of a cubic foot' per gal` available oxygen to the oil in the chamber to maintain the thermal conditions of conversion and to supply oxygen to increase the anti-detonating properties of the product, and vp assing heated oilfrom the` chamber to 'a stage maintained at pressure conditions reduced to the extent that the lighter fractions are distilled off. j

2. A process of converting petroleum oil consisting in maintaining the oil in a body at a conversion temperature and pressure in excess of 450 pounds per square inch in a conversion stage, reduclng the pressure in a vaporizing stage and recovering a distillate by condensing the evolved vapors, introducing a gas containing available oxygen into the oil in the conversion stage in sufficient quantities to maintain the existing conversion conditions of temperature and pressure, and in addition to supply oxygen for conibination with the hydrocarbons to increase the anti-detonating properties of the recovered distillate. f

3. A process of converting petroleum oil consisting in maintaining the oil in a body at a conversion temperature and pressure in excess of 450 pounds per square inch in a conversion stage, adding a gas containing available oxygen to the body of oil to maintain the thermal conditions of conversion and to supply oxygen for combination with the hydrocarbons to increase the antildetomating compounds therein, then passing the oil to a stage maintained at pressure conditions reduced to the extent that the lighter fractions are distilled off, refluxing and condensin the evolved vapors, and recycling the re uxed material through the conversion stage for treatment. e

4. A process of converting .petroleum oil,

'on the oil from the chamber in a vaporizing stage, and recovering a distillate by condensing the evolved vapors.

WALTER M. oRoss.

consisting in heating the oil in a coil and 

